gro: Disable frag0 optimization on IPv6 ext headers

The GRO fast path caches the frag0 address. This address becomes invalid if frag0 is modified by pskb_may_pull or its variants. So whenever that happens we must disable the frag0 optimization. This is usually done through the combination of gro_header_hard and gro_header_slow, however, the IPv6 extension header path did the pulling directly and would continue to use the GRO fast path incorrectly. This patch fixes it by disabling the fast path when we enter the IPv6 extension header path. Fixes: 78a478d ("gro: Inline skb_gro_header and cache frag0 virtual address") Reported-by: Slava Shwartsman <[email protected]> Signed-off-by: Herbert Xu <[email protected]> Signed-off-by: Eric Dumazet <[email protected]> Signed-off-by: David S. Miller <[email protected]>
zhenyw · Jan 11, 2017 · 57ea52a · 57ea52a
1 parent 1272ce8
commit 57ea52a
Show file tree

Hide file tree

Showing 2 changed files with 8 additions and 2 deletions.
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
@@ -2477,14 +2477,19 @@ static inline int skb_gro_header_hard(struct sk_buff *skb, unsigned int hlen)
 	return NAPI_GRO_CB(skb)->frag0_len < hlen;
 }
 
+static inline void skb_gro_frag0_invalidate(struct sk_buff *skb)
+{
+	NAPI_GRO_CB(skb)->frag0 = NULL;
+	NAPI_GRO_CB(skb)->frag0_len = 0;
+}
+
 static inline void *skb_gro_header_slow(struct sk_buff *skb, unsigned int hlen,
 					unsigned int offset)
 {
 	if (!pskb_may_pull(skb, hlen))
 		return NULL;
 
-	NAPI_GRO_CB(skb)->frag0 = NULL;
-	NAPI_GRO_CB(skb)->frag0_len = 0;
+	skb_gro_frag0_invalidate(skb);
 	return skb->data + offset;
 }
 

diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
@@ -191,6 +191,7 @@ static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
 	ops = rcu_dereference(inet6_offloads[proto]);
 	if (!ops || !ops->callbacks.gro_receive) {
 		__pskb_pull(skb, skb_gro_offset(skb));
+		skb_gro_frag0_invalidate(skb);
 		proto = ipv6_gso_pull_exthdrs(skb, proto);
 		skb_gro_pull(skb, -skb_transport_offset(skb));
 		skb_reset_transport_header(skb);